Western Cordillera and Adjacent Areas
This volume includes guides for 15 of the field trips held in conjunction with the 2003 GSA Annual Meeting in Seattle. Topics covered include Glacial Lake Missoula and the Clark Fork Ice Dam; the Sauk Sequence in western Utah; the geology of wine in Washington state; the Columbia River basalt and Yakima Fold Belt; Alpine glaciation of the North Cascades; and recent geoarchaeological discoveries in central Washington. Quaternary geology of Seattle, engineering geology in the central Columbia Valley, and the tephrostratigraphy and paleogeography of southern Puget Sound also are covered, as are trips to central Cascade Range and the White River.
Evolution of a polygenetic ophiolite: The Jurassic Ingalls Ophiolite, Washington Cascades
Published:January 01, 2003
Gregory D. Harper, Robert B. Miller, James H. MacDonald, Jr., Jonathan S. Miller, Ante N. Mlinarevic, 2003. "Evolution of a polygenetic ophiolite: The Jurassic Ingalls Ophiolite, Washington Cascades", Western Cordillera and Adjacent Areas, Terry W. Swanson
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The Ingalls Ophiolite Complex is a suprasubduction-zone ophiolite formed largely in a fracture-zone setting. Mantle tectonites are cut by a large, high-T shear zone overprinted by sheared serpentinite. Mafic complexes of ca. 161 Ma gabbro, sheeted dikes, and pillow lava occur as large blocks in the sheared serpentinite. An overlying Late Jurassic argillite unit contains minor chert, graywacke, and pebble conglomerate, along with lenses of ophiolite breccias. Detrital serpentinite forms some of these breccias, and mafic blocks in other breccias range up to hundreds of meters in diameter. Older basement is locally present in the ophiolite complex, includ ing...